2,566 research outputs found
Image-based Quantification of 3D Morphology for Bifurcations in the Left Coronary Artery: Application to Stent Design
Background
Improved strategies for stentâbased treatment of coronary artery disease at bifurcations require a greater understanding of artery morphology. Objective
We developed a workflow to quantify morphology in the left main coronary (LMCA), left anterior descending (LAD), and left circumflex (LCX) artery bifurcations. Methods
Computational models of each bifurcation were created for 55 patients using computed tomography images in 3D segmentation software. Metrics including crossâsectional area, length, eccentricity, taper, curvature, planarity, branching law parameters, and bifurcation angles were assessed using openâsources software and custom applications. Geometric characterization was performed by comparison of means, correlation, and linear discriminant analysis (LDA). Results
Differences between metrics suggest dedicated or multistent approaches should be tailored for each bifurcation. For example, the side branch of the LCX (i.e., obtuse marginal; OM) was longer than that of the LMCA (i.e., LCXprox) and LAD (i.e., first diagonal; D1). Bifurcation metrics for some locations (e.g., LMCA Finet ratio) provide results and confidence intervals agreeing with prior findings, while revised metric values are presented for others (e.g., LAD and LCX). LDA revealed several metrics that differentiate between artery locations (e.g., LMCA vs. D1, LMCA vs. OM, LADprox vs. D1, and LCXprox vs. D1). Conclusions
These results provide a foundation for elucidating common parameters from healthy coronary arteries and could be leveraged in the future for treating diseased arteries. Collectively the current results may ultimately be used for design iterations that improve outcomes following implantation of future dedicated bifurcation stents
Site-Dependent Differences in Artificial Reef Function: Implications for Coral Reef Restoration
There is an increasing use of artificial structure in coral reef restoration (for references, see Spieler et al., this volume). Often artificial reef structures are chosen for a restoration project simply because they were used elsewhere. However, it is questionable whether the results obtained at one restoration site can be extrapolated to another. In recent years, several studies have examined the effect of artificial reef site selection on formation of associated fish, algae, and/or invertebrate assemblages (Alevizon et al., 1985; Blinova et al., 1994; Bombace et al., 1994; Caley and St. John, 1996; Chang, 1985; Haughton and Aiken, 1989; Hixon and Beets, 1989; Jara and Cespedes, 1994; Kruer and Causey, 1992; Lozano-Alvarez et al., 1994; Moffitt et al., 1989; Relini et al., 1994; Sherman et al., 2000; Sherman et al., 1999; Sogard, 1989; Spieler, 1998; Tomascik, 1991). Although not designed specifically as coral reef restoration projects, the results of these studies lend insight into the problems of restoration. This paper is an overview of recent literature on site selection intended for resource managers interested in using artificial reefs in coral reef restoration. To that end, we re-examined the data from several studies comparing similar artificial reef structures at different sites
Artificial Substrate and Coral Reef Restoration: What Do We Need to Know to Know What We Need
To use artificial substrate effectively in coral reef restoration certain basic knowledge is required: (1) what is the artificial substrate expected to accomplish relative to the goals of the restoration effort and (2) what are the expected interactions of the selected substrateâs composition, texture, orientation, and design with the damaged environment and the biota of interest. Whereas the first point is usually clear, at least in general terms, the second is not. In this review, we examine: the functions of artificial substrate in restoration and some of the physical (i.e., composition; surface texture; color and chemistry; and design in terms of profile, shelter, shading, size and configuration, settlement attractants, and stability) and environmental factors (i.e., temperature, light sedimentation, surround biota, hydrodynamics, depth, and temporal effects) affecting these functions. We conclude that until substantial additional research is accomplished, the use of artificial substrate in coral reef restoration will remain a âbest guessâ endeavor. Areas requiring additional research are identified and some potentially promising lines of inquiry are suggested
A Qualitative Evaluation of Mental Health Clinic Staff Perceptions of Barriers and Facilitators to Treating Tobacco Use
Introduction: Veterans with mental health disorders smoke at high rates, but encounter low rates of tobacco treatment. We sought to understand barriers and facilitators to treating tobacco use in VA mental health clinics.
Methods: This qualitative study was part of a trial evaluating a telephone care coordination program for smokers using mental health services at six VA facilities. We conducted semi-structured interviews with 14 staff: 12 mental health clinic staff working at the parent study\u27s intervention sites (n = 6 psychiatrists, three psychologists, two social workers, one NP), as well as one psychiatrist and one psychologist on the VA\u27s national tobacco advisory committee. Interviews were transcribed and inductively coded to identify themes.
Results: Five barriers themes emerged: (1) competing priorities, (2) patient challenges/resistance, (3) complex staffing/challenging cross-discipline coordination, (4) mixed perceptions about whether tobacco is a mental health care responsibility, and (5) limited staff training/comfort in treating tobacco. Five facilitators themes emerged: (1) reminding mental health staff about tobacco, (2) staff belief in the importance of addressing tobacco, (3) designating a cessation medication prescriber, (4) linking tobacco to mental health outcomes and norms, and (5) limiting mental health staff burden.
Conclusions: VA mental health staff struggle with knowing that tobacco use is important, but they face competing priorities, encounter patient resistance, are conflicted on their role in addressing tobacco, and lack tobacco training. They suggested strategies at multiple levels that would help overcome those barriers that can be used to design interventions that improve tobacco treatment delivery for mental health patients.
Implications: This study builds upon the existing literature on the high rates of smoking, but low rates of treatment, in people with mental health diagnoses. This study is one of the few qualitative evaluations of mental health clinic staff perceptions of barriers and facilitators to treating tobacco. The study results provide a multi-level framework for developing strategies to improve the implementation of tobacco treatment programs in mental health clinics
Solid-state nuclear magnetic resonance of quadrupolar nuclei with applications to biological solids
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1999.Vita.Includes bibliographical references.by David S. Rovnyak.Ph.D
P-11 Social Support and Fundamentalism as Predictors of Religious Internalization
What variables are the strongest predictors of religious identification? Religious internalization can be broken down into identification, the full adoption of religious values, and introjection, a partial internalization of values. Fundamentalism is one variable thought to predict these motivational types. We defined fundamentalism as the degree to which someone holds their sacred texts as true. Additionally, social support relates to religious internalization. To measure these variables, two separate scales were used for each: Multidimensional Scale of Perceived Social Support and Basic Psychological Need Satisfaction Scale for social support, Intratextual Fundamentalism Scale and Revised Religious Fundamentalism scale for fundamentalism, and The Faith Maturity Scale and Christian Religious Internalization Scale for religious internalization. After extensive review of previous literature, it was hypothesized that measures of fundamentalism would be independent predictors of religious identification relative to social support. The results of this study were analyzed using a hierarchical linear regression and the results of this hypothesis were partially supported. Fundamental beliefs and a personal relationship with Christ were the predictors of religious identification after measures of social support were included; however, measures of social support accounted for minimal additional variance
UAS for Public Safety: Active Threat Recognition
The Center for Homeland Defense and Security identified an increase of active threat events, such as mass shootings, annually since 1999. Literature suggests that 90% of shootings were over before law enforcement arrived at the scene and the first responder response was limited to âsurround and containâ until Special Weapons and Tactics Teams (SWAT) arrived on the scene. Using Unmanned Aircraft Systems (UAS) to detect which individual was the threat and type of weapon used can provide useful information to increase the speed of the response for first-on-scene rather than waiting for SWAT if the type of weapon was known. A UAS equipped with a full spectrum sensor compared traditional red-green-blue (RGB) images to near-infrared (NIR) images in a simulated active threat scenario. A true positive rate (TPR) metric was used to measure the percentage of correctly-detected weapons consisting of either a knife, pistol, rifle, shotgun, or shovel at slant range distances of 25-, 50-, 75-, and 100-feet respectively. A convenience sample of 102 survey participants, recruited from constituents of the Airborne Public Safety Association (APSA) and DRONERESPONDERS was conducted to observe 48 randomly-presented images to determine which type of weapon was detected. The results suggest that survey participants could correctly detect weapons at a 12% greater rate with the NIR sensor than the RGB sensor; however, the pistol had the largest difference in TPR between NIR and RGB sensors. The pistol had an increased probability of detection by 33% when using the NIR sensor compared to an RGB sensor. Additionally, differences were also observed between slant range distances. The closest distance of 25 feet showed a 42% increase in participantsâ ability to correctly determine the weapon type compared to the 100-foot slant range distance. Therefore, using a NIR sensor-equipped UAS at flying a maximum slant range distance of 50 feet may help a first-responder determine the type of weapon before SWAT arrives on the scene
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